Filament in electric incandescent lamps and its manufacture.



PATENTED FEB. 11, 1908.

F. M. F. CAZIN. FILAMENT IN ELECTRIC INOANDESGENT LAMPS AND ITS MANUFACTURE.

APPLIOATION FILED JUNE 2, 1904.

Z E R M 00 a .0 M W V M UNITED STATES PATENT oEEIoE.

FRANCIS M. F. CAZIN, OF HOBOKEN, NEW JERSEY.

FILAMENT IN ELECTRIC INCANDESCENT LAMPS AND ITS MANUFACTURE.

Specification of Letters Patent. 4

Patented Feb. 11, 1908.

Application filed June 2. 1904- Ssrisl No. 210.870.

cation.

.flhe pur ose of the present application is of the same 0 aracter and in the same line of inventive evolution, as the a plications were for the sixteen patents issued to me under Nos. 523,460 523,4c1, 566,285-, 620,640-, 621,291, c21,292 640,366, 844,778 835,938, 786,729, 772,215, 7 60,849', 770,221---, 770,222--, 770,223 and 846,823 and. as ten other applications, yet pending, are. They all relate to improvements in electric incandescent lamps and in the methods and processesof their manufacture or to apparatuses used in and'for such manufacture. These entire patents with their s ecifications and claims contain informatlon, which those skilled in the line of electric-incandescent-lam i-making need to appropriate, in order to eep abreast with their art and in order to clearly understand the contents and apply the improvements specified in this ap lication. And my present pur ose is main y to secure patent on certain.

m0 ifications in my invention, which, though alluded to in some prior application or applications, were not there explicitlyenough specified and notsufiiciently disclosed for formulating on the stated specification and disclosures the proper claims for their protection by patent, or which were, under then prevailing rules, divided out of these prior applications on official demand.

I now desire to secure patent for the important, new and useful improvements as by me invented in the matter of the entire and main conductive element in all of its functional parts, including the non-incandescing or in-and out-leadin wires, or the parts thereof, which under Increased section or in more conductive material constitute the nonincandescing inand out-leading parts and including the partor parts, which either by less transverse section or by being made of decreased current conductivity quality or of increased current-resistance are heated and made incandescent and including the transition parts from one such functional part to such other functional part or parts, or that,

cation for such patent, filed on which is called terminals and which has the function of cooling by increased surface and of producing cohesion between parts of different materials and functions, and including the protection of such entire conductive element be it by their chemical insulation or by their surfacing or by their hermetically sealing and including their structure and com osition. And I desire to secure rotectlon by patent for my new methods 0 secandescent lamps, special attention be paid to the widening out of leading-in an eading-out parts of the conductive element, where different materials of and in such eldment have their longitudinal contact and where the parts of the conductive element longitudinally one another. MyPatent 'oin lqo. 621292, refers to such terminals, in sun-- dr wa s, namel as the cu ha (I termil ing which a: such are illu t ate d in the drawings, that are part-of the application or patent, as mentioned.v In the o al specictober 15, 1897, and bearing the Serial Number 655,312 there occurs on page 7, in the two last paragraphs the following, namely 2'- i It having been experienced, that in the incandescent lam s, using rare metal oxids in their luminous ody, with or without vacuum, the critical spot is, where the oxids and the filament come .in contact with one another, or with the inleading wires, I have devised cup-shaped terminals of the inleading wires for better. protection, hermetical inclosure and solid support of the cylindrical luminous body by its ends, and graphitic cement as counteracting or preventing reaction between essential parts. This application of a more than commonly secure connection between filament and luminous body of oxids on the one hand and the Wire terminals on the other handis caused by these oxids not being a mere film or coating but there being a real solid tubular body, able to support and strengthen the .2,"1900' cups or" accompanying the same show these cupsf or terminals in their relations to the functional parts of the luminant proper. In Figure 1 of the drawings to said patent the chemically insulating cover of the conduct- 5 ive element proper ceases 'to so insulate before the non-heated part of the conductive element, preferably platinum wires, leave the terminal in the direction towards the base of lamp. And the cups .is shown as filled with material, that is not identical with the oxids of the luminant proper, the same relation being shown in Figs. 4 and 5. But Figs. 2 and 3 on the contrary show the chemically insulating cover of the conductive element proper to reach beyond the terminals.

Whlle in the cited parts of specification only single terminals and not arallel plural terminals are mentioned, app icant has disclosed his method of employing such plural parallel terminals when in his application of iluly 24, 1893, (No. 481322) he stated as folows: 1

It is manifest, that the incandescent material may, be arranged on one of several 5 lines, each line terminating in a pair of circuit terminals, which canbe connected to separate pairs of inleading wires or to a common pair, as may suit the conditions. This constitutes another point of distinction from the lamps of commerce now in use.

Fig. 1, analogous to Fig. '1 in my Patent No. 640,366 and as shown in my application No. 3061 illustrates the case, when the circuit terminals are connected to one or a com- 5 mon pair of inleading wires. Fig. 2, illustrates the case, when the circuit terminals are connected to separate pairs of inleading Wires, though the pairs are in series, While as well they may be separately connected with 40 separate airs of electric poles. Fig.3 illustrates a ament with terminals consisting in successively increasing transverse section, in substitution of cup-terminals. Fig. 4 illustrates the cup-terminals in enlarged size.

5 The terminals, as alluded to in my prior disclosures, and as since further improved, perform the following functions, namely 1.) They connect electrically "the parts of the conductive element or elements, one class 5 of which parts has the function of conducting an electrical current, such as a plied to electric lamps, without offering sufficient resistance to cause essential increase of the teinperaturein such part or parts, and the other class of which parts has the function of offering sufficient resistance to cause increase of temperaturetherein to produce incandes-' cence or luminosity.

2.) They protect either class of such parts 0 against chemical reaction on one another,

while under electric current. And this rotection by the terminals, providing in t eir composition and structure'for chemical insulation (compare my Patent 620,640) as be- 5 tween these parts-classes, viz. by interposing between them some material such as metallic paste, which, preferably aluminiumthough a good electric conductor, has no chemical allinity for the material, that constitutes or occurs in either of the connected parts. 9

3.) They provide for increased and sumcient cooling surface at the above specified critical point, where by experience it is proved t at the resistance is the highest and the heat production is locally excessive. To obtain such increased and effective coolingsurface, I have introduced the comparatively large and mainly spherical terminals, such as shown with my application of March 2] 1899, (Patent 640366) and such as shown in 30 Fig. 4 of the drawings that are a part of this present application. v

4.) They rovide, by holding the ends of filament or filaments firmly to the effect, that they cannot change their position within the .5 terminals, and by means of the cohesive stiffness of the filaments themselves, for so mounting these filaments, that, as plainly shown in Fig. 2. of the drawing accompanying this application, they will in no part come into contact with themselves, but will by a twist given them, when being fastened in the terminals, and at each end in a direction contrary to the direction given the twist at the other end. This function of the terminals rests on the firm hermetical glass-sealing, by me so often described, by the use of melting glass-powder, as also indicated in the drawings, that form part of this specification.

5.) They firmly sup orf. themselves held and supported in turn y t..e inleading wires, that vary in thickness, according to the special requirements of the lamp, the luminantbody or structure pro er.

6.) The enlargement of t e inleading wires to cups or to their equivalents, preferably, as shown of s herical form and leaving a space inside, to e filled with the sundry functional matter and parts as above mentioned,

forming a solid entirety, fully apt to perform 1110 the functions assigned thereto.

It then remains for applicant to specify his further new improvement in the matter of the conductive element which relates to their hermetical sealing thereof, where they pass 11:] into the air-evacuated glass bulb.

In the'original application for the hereabove cited Patent No. 621,292, filed on October 15, 1897 ,itself a division mainly out of some prior applications in its main contents, there occurs on page 6 the following, namel a W 1811 the solid body, E, intended to become luminous, has been attached to the inleading wires f and f in a manner, that'125 will protect the free ends of the inclosed, filament e against the vehement reaction, produced, where it has its first contact with the platinumof inleading wires and the oxids, namely, by sealing the ends hermeticany further than at its extreme tip, but maintaining it for subsequent fusing the same 'concentrically with the (tubular or cylindrical) studs (1 and b.

Ihave repeated since then .on sundry occasions allusion to the thus stated method of sealing-in hermetically the non-heated part of the conductiveelement in electrical vacuum lamps. And I desire to direct attention to the fact, that all drawings filed by me of the seals, made with glassowder,

show the closed end of the part (D) 1n hemispherical or semi-spherical apex and surely not as compressed or squeezed from the outside into a flattened sha e, the tip being possibly or exclusively mo ified by the puncture made for passing the wires.

When a plurality of cou les of inleading wires is made instrumenta to the currentcarrying of the lamp be it with one or more pairs of pole connections the necessit results of giving to the central base part form of an inverted bottlewith a narrow neck and a wide body with a broad and convex closed end as shown in Fig. 2, and 3, and as called by glass-makers dew-dro s. In such or in similar cases I utilize e powdered glass. which is made use of in making 'oints or the assa e of the sundry wires a ermetical sea an which owder of neceS- sity is then s read over t e insideu of the glass-face, which fronts toward the luminant of the lamp, for the formation of a light refiecting face. And this is affected by selecting opaqueglass for making thereof the said powder. And the utility of the resultlng reflector is increased, by selectin its color, or that of the primarily =powdere and thereto fused glass, m-view of such rays being mainly reflected, which are most desirable in complementing the ray-com osition of the luminant to produce as near y as practicable an agreeable or white light.

Having so far specified the by me preferred form of the practically non-heat ng part of the conductive element in my improved lamps, applicant now proceeds to disclose certaln new and useful improvements in the matter of the material or materials to be used in these lamps for the conductive element at large, be it (as shown in the present art) different from one another in the central or luminant part and in the in-and out-leading parts, or be it eventuall as by me newly invented, of mainly an essenthe tially the same material in its entire length, the difference in resistance to current and in conse uent production of difierent temperatures eing brought about by difference intransverse section and by other material,

the selection that is associated to or with the one functiona part and not with the other functional art,;or brought about'by these causes joint y. i

The attempt to make the entire conductive element in electric incandescent lamps of the metal platinum has been madebut the infusible fire-stable metals sin ly' or in allo s of the ruthenium-osmium c ass, and

pre erably the natural iridosmin or osmiridium mainly or essentially with or without metal of lower -temperature of fusion referably platinum and with or without ot er assoclate materials in and for either part ofthe length or for the entire length of the conductive elements in electric incandescent lamps.

The art of the conductive element, which is offering the higher resistance to the elec- ..tric current and which in consequence constitutes its luminant part is. preferably made by me of three concentrical arts, namely 1, the core; 2, the chemica insulation and mainly, 3, the light emitting surface. And these main arts are not as such essential in every hi er-resistanceart of the conductive element, which sci-evidently con-Q sists of solid matter,-except that. it has a light-emitting surface, as indicated under 3. The core and the higher-resistance-part may be one or identical, and the chemical insulation may not'be' needed or may have its origin in some inter-reaction between a core and a special surface-matter, just so as the special surface by some reaction on the outer matter may be modified. Or as indicated in my Patent No; 844,778- and in special in its 13. claim, and as indicated in my application of Oct. 15, 1897, and as since contlnuously reiterated, namely in the following words:

I consider as m invention the arrangement of a carbon-fi ament to form the negative pole in an electrolytic bath in a loopshape, similar to the sha in which it is to be used in thelamp, wit out direct connection with'the ositive pole (such as used in the common ashing process). And I consider-as art of my invention the thereto adapted orm of the metal, used as the posip tive pole 'in the bath, by which form the carbon-loop is surrounded in close proximity and mainly uniform distance by a plate of metal, that acts as the positive pole, which cipitating a solid coaton a carbon-filament, byattachin both ends of the filament to the negative po e of the electrolytic ap aratus, immersing the filament-loop into theelectrolyte and surrounding the same at some distance with a metal cathode of such form as is adapted to face' the filament at uniform distance mainly. (Compare: testimony in behalf of Cazin in interferenceproceedmgs No. 24,614pa e 6.)

' The core itsel may be constituted of some conductive material in the form of a filament, bent into theshape intended for it to possess in the finished lam such core being then further electrolyticall y lated.

And yet one other method for building up my improved lowers and filaments, may be described as f0 lows: I had fully ascertained, that the infusible (at the temperature of the white-incandescing glower) metals improved in conductivity, when alloyed with one another,but even as such and as stated, they were deficient in cohesivenessand ductility. For reasons of similarity in specific gravity as well as of atomic proportion platinum has heretofore been ranged as of one group with the more infusible metals osmium iridiiiin, etc. but of all of these platinum exclusively had been tested in the earlier stagesof electric li ht-construction and had proven unavaila Ie on account of its fusion at or slightly below its temperature of white incandescence. Withal platinum possessed the so much Wanted cohesiveness in electrolytic deposit and otherwise. It was therefore a very natural evolution of my invention, that I should use platinum in a natural fraction of the alloy as a corrective to render the natural iridosmin more available for my purpose. To render this practicable,-I had to determine on an electrolyte, in which the diflerent metals to the alloy-dc osit were in an analogous. composition,t at they all might be reacted upon by the electric current in an analogous as well as proportionate'manner. There is then one-kind of a solution, fit to serve as 'electrolyte, in other. words,answering the requirements, as hereabove by me specified,- namely'the analogously composed chlorids of potassium or sodium in the salts: l, osmium-potassium chlorid; 2, iridium potassium chlorid; 3', latinum-potassium chlorid, as well as the sa ts of sodium-chlorid with the threezdiflerent similar high-fusion metals. a

All six salts are repared by the Wohler ll known in chemical art decomposing infusible metals in a current of chlorin.

'In the, natural iridosmin the pro ortion of the two metals is not found to be armonious with a composition in pro ortion as indicated by their atomic weig ts. I found it sufficient in practice to add solution of iridium chl'orid, until the deposit assumed its satisfactory appearance and'qualities, a remedy adapting itself well to the different composition of natural iridosmin. It is further self-evident, that the specified metals that form as such the anode, must there be as nearly as practicable, in proportions, that are analogous to their atomic weights, though'they ma be present as of different relative'valenzia relation.

With the anode in'the shape of fine livision (powder) and properly proportioned the deposit is a true alloy and does not discard the one metal after the other in an eventual sintering process, as the alloy reaches the different points of fusion of the single metals, but has a very high fusiontemperature common to all as their alloy. This temperature is above their temperature of white incandescence, as by me practically proven, in other words it fully answers the purpose of being made into luminants for electric incandescent lamps ;the vacuum being eventually the necessary protection against combustion of the osmium, which protection may also eventually be intrusted of producing white or even blue-white incandescence, And such increase of coheslveness, be it for intermediate servlce or for permanent, I produce in sundry ways, but mainly by a flashing of the luminant resultlng in a deposit of a coat of more cohesiveness than that of .the stated part of the conductive element, such as a coat of carbon or of any other functionally suitable material.

That I have mentioned a vacuum as.

eventual protection of and for my improved filament or glower mainly consisting of a practically infusible allo of metals of the platinumgroup,'so ca ed,-does not be.

intended to indicate, that I may not as'well use an atmosphere, be it permanent or continuously supplied of some stable or unstable gas orgases in connection with my improved metal-filaments, such as hydrogen, or a gaseous or vaporous hydro-carbon. And in connection therewith inan inner bulb, I may use an outer or extra bulb or bulbs and air exhaust the space between the inner and outer bulbs for'th'e purpose of heat-conservation and protection.

be made to serve special purposes as to the linal character of the metal etc. luminant.

So for instance I may use in place of the.

potassium-chlorid in the solution of doublemetal chlorids the osmiate of potassium etc., in which case I further dilute the electrolyte to leave it but slightly alkaline. It then remains to speak of method and manner of passing the conductive element into or out of a glass-inclosed space, which may be air-exhausted or .be filled with inert gas or with gaseous or vaporous h dro-carbon etc., out of or into a space within and filled with atmospheric air. M manner and method differs in this from t 1e old art, that instead of selecting the wire-metal to conform, as platinum does in coefficients of contraction and expansion with the glass, I' compound the glass-mass to produce a'glass, the said coefficients of which conform with those of my conductive element,-where it passes the glass and where a hermetical seal is intended.

Applicant hasinex erimentingascertained, that longevity of tlie conductive element and lamp is fostered by expanding the protection of such element over and beyond the immediate requirement of hermetical sealing,

by prolonging the glass-embedding beyond sively but they also are practically infusible and therefore they are peculiarly adapted to be used in electrical luminants, as has by me been practically proven. As the metals, that belong to the class, by me preferred in making up my improved filaments, I nevertheless' abstained from specifying exclusively those of the rutheniumosmium class, but I specified them in mg prior application as infusible oxygeniza 1e, as metal having affinity for oxygen and high point if fusion (Com are the c aims in my PatentNo. 835,938

- issue p on my application of Febr. 2, 1899, on

Nov. 13, 1906, as well as lines 41 to 55) and as such metals I also specified Wolfram (tungsten) uranium, manganese, rhodium,

iridium and thorium, and nowhere has their number been limited but by their cited natural ualities. Tin is also mechanically powdera le but only at the high temperature of 200 and also it is almost the only metal -the central part to a big which forms a true alloy with those powderable and infusible metals. Of .this tin-pulverization I take advantage in mixing the powdered infusible metals 1n proper or suitable pro )ortions with pulverized tin and eventual with pigment admixture. This mixture 1 may use in the form of fine )owder or I may add to the mixture eventua ly collodion or glycerin or both or some volatile oil or other matter to make a paste of plastic or liquid consistency. In proper consistency this metallic paste is squirted, and preferably so into the inside of a glass tube of suitable dimensions. I may aid in'such filling by air exhaustion of the tube or by air pressure on the paste or b both, at different ends of the tube. Mainly avoidin other than metallic components, I may a so fuse and cast the specified alloy with or without admixtures into the tube-channel of a preferably U-shaped glass-tube, using pressure and suction (air-exhaustion) on the molten metal etc. on the o posite ends of the heated tube. It should t en be understood, that the transverse section of the glass-tube used in such manipulation has been selected or determined onthe ground, that the wire or filament or conductive element therein primarily formed or formable be at least of such transverse section, that the lamp-current may pass the same, without practically or perceptibly heating the same, or be adapted to the function of inand out-leading of electric current of suitable function. It then remainsto draw out, roll out, thin out the central part or parts of the tube and fillet to a reduced section adapted to be heated by said current mainly by the aid of heating strumental to produce sundry useful effects I such as the carbureti of metals or as the discarding, if present, 0 metals of lower temperature of fusion or even of the remammg portion of the glass-tube or embedding from the central part of the conductor. Precaution must be taken against oxygenation of the fillet, eventually by handling the same in vacuo. (Com are my application No. 141,501 for bell 1ar'incloscd plating apparatus, etc.) v

In the matter of discarding from the filletalloy the metals of lower temperature of fusion it should be understood, that it has been observed by me, that in heatingjhe tube to differential temperatures, and mainly er temperature than the end parts, the low fusion point metal withdraws from the central art into the end parts, where they need not e discarded but may there even aid in the befitting thereof to conducting without practical heat production.

It further remains for a plicant to state his method of building up 0 different metals, the in and out-leading parts of his improved conductive element as well as the central part thereof viz., the luminant part, and one of his preferred methods as a plied to the efl'ect of securing long hermetica seals such as by him described.

It is a matter of known art, to select platinum as the metal of which to make inleading wires be it exclusively or in part. And it has been customary to make the hermetical seal mainly around platinum-parts of inleading wires and patent has been issued (No. 444530) on sealing, in the same seal, two metals and for sealing all of the plat-inum parts into the seal, wlnle different metal is used both inside of the bulb and outside of the seat.

It is applicants selection and method to I make the main or entire length of the conductive element in the lamp of mainly the same metal or of the same metals or of an alloy mainly of the same character, though in the making of different parts functional differences in composition as well as in transverse section may be effected. And in carrying out this selection or method the following conditions are complied witlnnamely:

1. ,Equal expansion and contraction with the glass that forms the seal the equalization being effected by adapting the composition of the seal-glass to the expansion and con-- tracting qualities of the selected metal and 2. Practical infusibility in the central or lummant part with proper provision for cooling the intermediate or terminal parts---between central and end parts. to a non-formdestroying temperature.

3'. Suflicient transverse section of the end parts of the conductive element to mainly conduct the electric current asemployed in the lampwithout resistance to the current to effect practical heating thereof.

I now shall describe a method for making wires of these infusible metals mainly of the osmium-ruthenium class.

In one of my applications for patent on" v electric incandescent lamps, filed on Feb. 2,

1899 and allowed on March 22, 1901, I claimed filaments made in part or wholly of one or of more of these metals. I now make of these metals mainly a continuous conductive element for my improved electric vacuum lamp, and I pass from the ractically non-heated part, which I pre erably not only hermetica ly iass through the lass seal but which I coat t iroughout with glass, to the luminant part thereof by means of re,-

ducing by degrees the transverse section of the conductor thereby increasing its resistance to current, between oints where the luminant part proper of t e conductor be gins and ends. And I now describe more specifically one of the sundry processes by me employed for producing a continuous conductive element, having difierent functions in different parts thereof, namely the method of casting the stated metals into a wire, though I may also treat all the'compound parts as a mixture in the form of fine powder. I produce an alloy of the infusible metal or metals with tin or any other suitable metal and cast a wire of suitable minute transverse section in a heated vertical U- shaped glass-tube aiding in the purpose by exhausting the air from the other end of the tube, while the molten alloy, by means of a funnel-expansion is poured into the other end and by adding eventually pneumatic pressure at the pouring-in-end, while the liquid alloy is entering the tube mainly by means of its own gravity.

As long as the tube is of suflieiently high temperature to keep the alloy liquid or plastic the tube together with the cast wire can be drawn out to decreasing transverse sections. In such drawing out operation by hand or under suitable rolling pressure the alloy and the plastic glass may be made to adhere to one another or to readily part from one another according to the provision made prior to the inserting of the metal into the glass tube in the way of producing either effect by a suitable coating of the tubular interior.

When I desire to cause ready parting I prepare a borax coating thereof by eva o'- ratmg a borax solution on the interior wall y revolving the tube containing such solution until complete evaporation of the solvent has taken-place.

When I desire to cause adhesiveness, the

preferable case I prepare the tubular inside y the use of .fluoric acid to become comparatively roughened and by treating the so roughened glass-face with a material of stronger basic effect than the base used in the composition of the glass, as for instance caustic potash against oxid of lead.

The thus prepared tubes are ready to be used as mol s for the cast wire and the alloy for causing the wire is preferably composed of 9 parts lnfusible metal and one part platinum and I may add asphaltum bitumen to cause porosity and to act as temporary pigments.

I do not confine myself in the carrying out of these new and improved methods exclusively tothese metals named but I may use other metals in alloy therewith, or use some of them and others not. Neither do I in thus making wire luminants confine myself to the exclusive use of these metals, but I I may use co-jointly with them, be it as core or as coatings rare-metals and their oxids also. That which I claim as my invention,'is:-

1. A filament in an electric. incandescent lamp which filament consists of a core, which is an electrolyticall metalized carbon-fillet, and of'concentrical ayers thereon, the transverse section of the two ends of which filament increase to a thickness-at'the extreme ends, which thickness increases the conductivity of the filament to the eflect,tha t the terminals do' not become heated under current. Y I 2'. A filament in an electric incandescent lamp, which consists of a central core and of adhesive concentric'al layers thereon, the layers consistin of electrolytical deposits, and the ends 0 which filament increase in thickness towards the terminals.

3. A filament in an electric incandescent lamp which consists of a central'core and of adhesive concentrical layers, the layers consisting of electrolytical deposits,being thicker at the ends of the filament than along its central main part.

4. The method of manufacturin filament in electric incandescent lamps, whic methodconsists in electrolytically plating on a core an adhesive concentrical coating of metal.

5. The method of manufacturm filaments in electric incandescent lamps, whlch method consists in electrolytically plating on a central core an adhesive coat, which consists of layers of metal. t

6. The method of manufacturing filaments in electric incandescent lamps, which method coating to the effect, that the plated filament is thicker near its end than in its main middleart. P 8. The method of manufacturing the filament forelectric incandescent lamps, which consists in electrolytically plating concentrical layers on a central core. v

' FRANCIS M. F; OAZIN.

Witnesses: r

CHAS. C. WASHBURN, MINNA E. CAZIH. 

